Full movie description "BraveStarr Big Thirty and Little Wimble":

Young Prairy Person Wimble chooses Thirty/Thirty to be his temporary (foster) father. When BraveStarr doubts Thirty/Thirty's abilities to take care of the kid, Thirty/Thirty enrolls Wimble in Miss Jenny's class at Fort Kerium. But Dingo outlaw Howler sets a trap for BraveStarr derailing Wimble and his classmates when they go on a field trip.